NOYEMBEE 27, 1914] 



SCIENCE 



771 



objects re-photographed have occurred in the in- 

 terval, these changes seem not to be appreciable, 

 or at most, are exceedingly small. The conclusion 

 drawn from this fact is that the nebulae concerned 

 are very remote, and therefore are enormous in 

 linear dimensions. These provisional conclusions 

 apply to many of the large irregular nebulse, such 

 as the Orion and Trifid nebulse, and to many of 

 the more prominent spirals, including the great 

 spiral in Andromeda. 



EwDiN B. Frost: An Interesting Stellar System. 

 Observations have been continued on the spec- 

 troscopic binary p Cephei, which has the remark- 

 ably short period of 4''34'°. Some features of the 

 system are discussed, and reference is made to the 

 detection at Berlin of variations in the star's 

 brightness by the photo-electric method. 



George E. Hale: The Direction of Rotation of 



Solar Storms. 



It is well known that cyclones and tornadoes in 

 the earth's atmosphere rotate in the right-handed 

 (clockwise) direction in the southern hemisphere 

 and in the left-handed direction in the northern 

 hemisphere. What is the case for solar storms? 



The existence of a magnetic field in sun-spots, 

 supported by other spectroscopic evidence, proves 

 that sun-spots are electric tornadoes of immense 

 size. The direction of rotation of the spot-vortex 

 is given by a simple spectroscopic observation. 



The results were at first confusing, as spots 

 rotating in both directions were found in the same 

 hemisphere. But it soon appeared that sun-spots 

 usually occur in pairs, lying close together on a 

 nearly east and west line, and always having 

 opposite directions of rotation. Tabulating the 

 polarities separately for the eastern (following) 

 and western (preceding) members of bipolar pairs, 

 we find (with very few exceptions) that the di- 

 rections of rotation for preceding or for following 

 spots are opposite in the northern and southern 

 hemispheres. 



Prior to the recent sun-spot minimum the pre- 

 ceding spots of the old cycle rotated left-handedly 

 in the northern and right-handedly in the southern 

 hemisphere, as in the case of terrestrial storms. 

 Since the minimum the direction of rotation has 

 been reversed. But the spots of the old cycle were 

 all in low latitudes, while those of the new cycle 

 are all in high latitudes. Thus there probably 

 exist in each hemisphere a high latitude zone, in 

 which preceding spots rotate right-handedly in the 

 northern and left-handedly in the southern hemis- 

 phere, and a low latitude zone, where preceding 



spots rotate left-handedly in the northern and 

 right-handedly in the southern hemisphere. 



J. C. Kapteyn and W. S. Adams: On the Sela- 

 tions between the Proper Motions and the 

 Sadial Velocities of the Stars of the Spectral 

 Types F, G, K and M. 



(1) The radial velocities furnish a very thor- 

 ough test of the theory of the star streams. The 

 results found for the F, G, K and M stars are in 

 close agreement with those we should expect from 

 the theory as derived from proper motions. (2) 

 The radial velocities of the stars of the smallest 

 proper motions show the effects of the two star- 

 streams with the same certainty as those of the 

 other stars. The existence of the two star-streams 

 is, therefore, proven at the greatest distances for 

 which we have adequate data. (3) The K stars 

 behave in general like the other stars, but there 

 are a few exceptional cases. These do not appear 

 to be due to the absence of the second stream. 

 (4) For all of the spectral classes the average 

 radial velocities show a regular increase with the 

 proper motion. (5) Such a change of radial 

 velocity is a necessary consequence of a velocity 

 distribution (for the peculiar motions) different 

 from that given by Maxwell's law. (6) A first 

 approximation to the velocity distribution has been 

 derived for the K stars. It explains the change 

 of velocity with proper motion in a satisfactory 

 manner. (7) Some positive indications have been 

 found of a change of radial velocity with absolute 

 magnitude, the brighter stars moving more slowly 

 than the fainter stars. 



S. B. Nicholson: Discovery of a Ninth Satellite 



of Jupiter. 



A satellite of Jupiter was discovered by means 

 of photographs made with the Crossley Reflector 

 of the Lick Observatory on July 21 and 22, 1914. 

 These photographs were secured in order to de- 

 termine positions of the eighth satellite, and the 

 new object was in the same photographic field. 

 The ninth satellite is considerably fainter than the 

 eighth, being estimated at about the nineteenth 

 magnitude. Additional observations of the new 

 satellite have been secured in August and Sep- 

 tember. The preliminary orbit, computed under 

 Mr. Leuschner's direction, shows that the orbital 

 motion is retrograde, that the first estimate of the 

 period is approximately three years, and that the 

 other elements of the orbit are similar to those of 

 the eighth satellite. 



